- Bring large pot of water to a boil for noodles over high heat.
- Make broth: separate stems from fresh shiitakes; set caps aside.
- Place stems in medium saucepan along with kombu, dried shiitakes, ginger slices, onion, shoyu, sake and 4 cups water.
- Bring to a boil over high heat.
- Remove kombu, reduce heat to medium and simmer until liquid is reduced by half, about 25 minutes.
- Meanwhile, slice reserved shiitake caps and set aside.
- Add noodles to boiling water; stir to prevent sticking.
- Cook until just tender, 6 to 8 minutes.
- Drain, rinse under cold running water and drain again.
- Transfer to large bowl; stir in sesame oil and 1 teaspoon shoyu.
- Set aside.
- Set wok or large skillet over high heat and add peanut oil.
- Immediately add sliced shiitake caps and stir-fry 1 minute.
- Add remaining 1 tablespoon shoyu and stir-fry until shiitakes are tender, 1 to 2 minutes.
- Add cabbage and stir-fry until tender, about 3 minutes.
- Remove from heat.
- Season with freshly ground pepper to taste.
- To serve, strain broth, discarding solids.
- Have garnishes ready.
- Divide noodles among 4 wide bowls or pasta plates.
- Add stir-fried vegetables then ladle over some broth.
- Top with mound of daikon, some nori slivers and chopped ginger.
- Pass wasabi mixture separately so that each diner can flavor broth to taste.
- Serve hot.